Tympanometric Changes at 226 Hz and 678 Hz Across 10 Trials and for Two Directions of Ear Canal Pressure Change

Abstract

The influence that repeated tympanometric trials have on the aural-acoustic admittance characteristics of the middle-ear transmission system was studied in 24 young adults. The 226-Hz and 678-Hz data were generated by concurrently digitizing the conductance and admittance tympanograms at 25 daPa/s for both ascending and descending pressure directions. Ten successive trials for each frequency and direction of pressure change were made. Changes in admittance corrected for ear canal volume across the 10 tympanometrie trials were computed. The results demonstrated that generally admittance increases as the number of trials increases. For many subjects, the complexity of the tympanometric configuration also increases across trials. The results from eight subjects with single-peaked 678-Hz tympanograms were compared with the results from eight subjects with notched 678-Hz tympanograms to explain the mean decrease in susceptance across tympanometric trials. Finally, the pressure peak locations of the conductance, susceptance, and admittance tympanograms were evaluated and are discussed. The effects that differences in peak pressure location have on the computed static admittance values are presented.

Effects of Consecutive Wideband Tympanometry Trials on Energy Absorbance Measures of the Middle Ear

“…To minimize the tympanometric preconditioning effect in research on tympanometry, previous investigators suggested collecting desired data after three to five tympanometry runs (Gaihede, 1996;Wilson et al, 1984). Our study has demonstrated that the second and third trials of WBTymp account for more than half of the total EA change by eight trials.…”

“…Previous studies on nine to 10 successive runs of 226-and 678-Hz tympanometry have revealed a systematical increase in acoustic admittance of the middle ear by approximately 12% to 14% (Gaihede, 1996;Osguthorpe & Lam, 1981) or a slightly higher percentage (Wilson et al, 1984). These studies also observed that about half of the total change occurred at the second trial.…”

“…Our study on aEA tests after eight WBTymp runs has demonstrated comparable outcomes in the increase of EA at low frequencies: approximately 9% for 0.223 kHz, 14% for 0.5 kHz, and 20% for 1 kHz. The underlying mechanism of the change of acoustic admittance by repetitive tympanometry trials has been suggested as an alteration in the viscoelastic properties of the eardrum due to repeated pressure loading on the eardrum (Gaihede, 1996;Wilson, et al, 1984), thus demonstrating that compliance at the eardrum increases (stiffness decreases), or the eardrum is preconditioned (Gaihede, 1996). This can also account for the increase of EA that occurred with consecutive WBTymp runs.…”

“…middle ear. Wilson et al (1984) observed that acoustic admittance of the middle ear increased in single-peak 678-Hz tympanograms, but decreased in notched tympanograms, with repetitive trials. A recent study on successive 1000-Hz tympanometry trials also revealed similar results (Carazo & Sun, 2013).…”

“…It measures acoustic admittance or impedance in the presence of a low-frequency probe tone (e.g., 226 Hz) and with air pressure varied in the ear canal. Previous studies revealed that admittance of the middle ear in low-frequency tympanometry systematically increased with repetitive testing (Osguthorpe & Lam, 1981;Wilson, Shanks, & Kaplan, 1984). Studies on test-retest reliability of low-frequency tympanometry also observed higher admittance for the repeated test (Gaihede & Ovesen, 1997;Karzon, 1991).…”